Two studies on reactivity to heteromodal stimulation as a function of anxiety will be completed. In one, subjects are divided on a test of manifest anxiety; in the other they are divided into a control group and a group of patients with a psychiatric diagnosis of "acute anxiety reaction." The purpose of the studies is to test the hypothesis that anxiety is associated with a defect in inhibitory capacity for reactivity to stimulation. Unlike previous studies in our laboratory, noise bursts will be combined with light bursts of sufficiently short duration (.001 sec.) so that the possibility of interference from stimulus-induced blinking is eliminated. Four studies on anxiety in sport-parachuting will also be undertaken. One, an intensive study of several individuals, will examine why people jump, and will explore common and individual mechanisms for coping with the stress of jumping. Another will examine the content of the dreams of sport parachutists as a function of experience-level and of time to a forthcoming jump. A third will examine physiological reactions and coping mechanisms exhibited by parachutists as they observe a film of parachuting. The aim in this study is to compare a real-life source of stress to the same stressful situation exhibited in a film. Time permitting, a fourth study will be done comparing the psychophysiology of euphoria and fear as exhibited, respectively, by novice parachutists after and before a first jump. A final study will be done comparing self-reports of experiences of intense threats to life and limb with self-reports of experiences of intense threat to ego. Commonalities and differences in coping techniques and in the nature of the anxiety experience in each type of situation will be examined.